This proposal seeks support for a replication of the National Comorbidity Survey to be carried out in the year 2000, a decade after the original NCS. If funded, the replication survey would be administered to a new sample of 10,000 respondents in the age range 15 plus in conjunction with an already funded NIDA- supported reinterview survey of the original respondents in the NCS sample. There are two specific aims. The first is to investigate time trends and their correlates over the decade between the two surveys. We will investigate trends in both the lifetime prevalences (so-called "cohort effects") of DSM disorders and in recent prevalences of these disorders. We will examine sociodemographic correlates of these trends, such as the possibilities that the sex difference in depression has decreased over the last decade and that the mental health gap between rich and poor people has increased. We will also examine trends in patterns of service use for these disorders, focusing on changes in the proportion of people with disorders in treatment, in the distribution of treatment across service sectors, in treatment intensity and adequacy, and in treatment dropout. We will also examine trends in a number of policy-relevant predictors of seeking treatment, including perceived need, perceived efficacy of treatment, and barriers to seeking treatment. The second specific aim is to generate nationally representative data for the U.S. in the year 2000 that will be used as part of the World Health Organization's (WHO) World Mental Health 2000 (WMH2000) Initiative. Under this aim we will coordinate with investigators in a dozen other countries around the world who are working with the WHO to carry out mental health needs assessment surveys in the year 2000. The surveys will ask parallel questions about the 12-month prevalences of seriously impairing and persistent mental disorders, treatment of these disorders, and the sociodemographic correlates of disorders and treatment. We will also estimate the societal costs of mental disorders from the perspective of the ill person, their employers, and the total society. A public use dataset that can be accessed by many students, researchers, and health policy analysts who need benchmark data of the sort provided by the proposed survey will be prepared and made available as soon as the data are collected and cleaned. In conjunction with the data release we will hold summer workshops in the use of the public dataset for two years after release.